Study on the synergistic effect of NaOH and CuSO₄ in aquathermolysis upgrading

The development of heavy oil has become increasingly important due to the demand of human society for energy. The in-situ upgrading is a technology using transition metal catalyst to reduce heavy oil viscosity to enhance oil recovery. This work revealed the Cu atoms of CuSO₄ entered the heavy oil molecules to increase viscosity, and the NaOH can inhibit this viscosity increasing effect to improve the catalyst activity of CuSO₄. The composite catalyst NaOH/CuSO₄ was proved to decrease the viscosity by 81.43% at 300 °C. The further analysis showed that the effect of NaOH was attributed to the competitive reaction mechanism and production of the Cu and CuO_x. These conclusions are helpful to understand the aquathermolysis upgrading mechanism and develop the inexpensive and efficient composite catalyst.